Had a problem with the Mg34 I was shooting a lot and overheated the barrel. I reloaded pressed 6 to change the barrel went to town with a couple more drums overheated again, reloaded pressed 6 couldnt change the barrel. went to the ammo station to get more ammo thinking it would give me another barrel but nothing I could do would let me fire again. Anyone else have input about this besides dont overheat the gun?